Currently, mobile phone systems, and communication systems, such as a wireless local area network (WLAN), and the like, are widely used. In the field of wireless communication, in order to further increase a communication speed and a communication capacity, there are continued discussions about next-generation communication technology. For example, The 3rd Generation Partnership Project (3GPP), which is a standards body, has completed or examined the standardization of a communication specification called Long Term Evolution (LTE) and a communication specification called LTE-Advanced (LTE-A) based on LTE.
In such a communication system, a wireless base station allocates a wireless resource, generates a control signal including an allocation result, and transmits the control signal to a mobile equipment. Wireless resource allocation includes specific frequency allocation or specific time allocation. The mobile equipment performs wireless communication with the wireless base station in accordance with a wireless resource included in a control signal, and the wireless base station also performs wireless communication with the mobile equipment in accordance with the allocated wireless resource.
The wireless resources are limited and, in order to increase use efficiency thereof, the wireless base station minimizes wireless resource allocation to a mobile equipment in a non-communication state in one hand, and allocates a wireless resource to a mobile equipment in a communication state on the other hand. Therefore, when a non-communication state continues for a certain time, the wireless base station releases a wireless resource allocated to the mobile equipment. In this case, a timer that measures a non-communication state and triggers release of a wireless resource will be referred to as, for example, a wireless resource release timer, occasionally.
However, there are cases where a control signal is generated between the wireless base station and the mobile equipment and furthermore between the wireless base station and a higher-level device by release of a wireless resource and reallocation of a wireless resource thereafter, and the control signal is exchanged. There are also cases where, when release and reallocation of a wireless resource is frequently repeated, the generation and exchange of a control signal increases to impose a large processing burden on each device in the communication system.
There are also cases where, for example, the mobile equipment and the higher-level device set a transmission control protocol (TCP) session and exchange a data stream and the like, based on the TCP session. In such a case, when a non-communication state continues, the TCP session is released in a higher-level device, or the like. Due to release of a TCP session, the occupancy of network resource of the TCP session does not occur, and congestion of data streams is not caused. In this case, a timer that triggers release of a set TCP session will be referred to as, for example, a TCP session release timer, occasionally.
There are cases where, due to a difference between two times, that is, an expiration time when the wireless resource release timer expires and an expiration time when the TCP session release timer expires, for example, the following two states occur. FIG. 16A and FIG. 16B are diagrams illustrating examples of the states.
A first example is a state where, as illustrated in FIG. 16A, the TCP session release timer has not expired at the time when the wireless resource release timer expired.
In this case, for example, the wireless base station releases a wireless resource in accordance with an expiration of the wireless resource release timer (S200). Thereafter, in accordance with an expiration of the TCP session release timer, the wireless base station receives a TCP session release request from the higher-level device (S201). Next, the wireless base station resets the released wireless resource (S202). Then, the wireless base station transmits a TCP session release request to a mobile equipment using the reset wireless resource (S203).
A second example is a state where, as illustrated in FIG. 16B, the wireless resource release timer has not expired at the time when the TCP session release timer expired.
In this case, for example, the wireless base station transmits the TCP session release request, which has been received from the higher-level device to a mobile equipment, using a set wireless resource (S210). At this transmission of the TCP session release request, in the wireless base station, the wireless resource release timer is reset in accordance with transmission of the TCP session release request (S211). Thereafter, when the wireless resource release timer expires, the wireless base station releases the wireless resource (S212).
As related techniques for communication, for example, there are the following techniques.
That is, there is a technique in which, in the case where hypertext transfer protocol (HTTP) communication between a mobile telephone and a content server is relayed, when a gateway server receives a release report signal indicating that a wireless link or a wire link is disconnected, the gateway server immediately releases a TCP connection with the mobile phone.
Using this technique, a connection type communication may be controlled so that increase in traffic of a network is reduced and a useless occupancy of a network resource does not occur.
There is another technique in which, when a moving body exchanger identifies an IP address, FIN, and ACK from one terminal side to detect data transfer and identifies an IP address and ACK from the other terminal side to detect data transfer, the moving body exchanger releases a communication channel corresponding to a mobile equipment number thereof after IP address exchange.
Using this technique, effective use of wireless frequency bands may be allowed, a statistically multiplexing effect may be increased, and also increases of the signal processing scale and the device scale may be reduced. As related art non-patent documents, there are 3GPP TS 25.331 V12.2.0 (2014-06) and RFC793. Japanese Laid-open Patent Publication No. 2001-358760 and Japanese Laid-open Patent Publication No. 2003-110622 are patent related art patent documents.